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Brian Carey
PL SC 403
Research Paper
The Effects of Redistricting Laws on Polarization
Every ten years when new congressional districts are drawn and seats are reapportioned
to states, the debate about the effect or fairness of redistricting heats up. Polarization is looked
at again and again in its relation to the redistricting process and while there is disagreement
about the amount redistricting has affected the polarization in congress, there seems to be
consensus that there is some small to moderate effect. Assuming that polarization in congress is
bad for democracy, then lowering polarization by a small to moderate amount would be an
important achievement. Do certain State’s individual redistricting laws have greater effects on
Polarization in the U.S. House of Representatives?
Introduction
Immense research has been put into the fields of Polarization, Redistricting, and the
correlation between the two. The DW-Nominate score is the leading measurement for the
polarization levels of Congress, and has concluded that we are becoming more polarized in each
new congress. This measure of polarization has led to the vast amounts of research available on
the subject of polarization. Studies have found agendas becoming more extreme (Sulkin and
Schmitt 2014), and that polarization leads to gridlock (Jones 2001). The cause of polarization
appears to be political activists (Layman, Carsey and Horowitz 2006), however to say that there
was any one cause of polarization would be foolish. Redistricting has raised the cost of voting
for citizens (Hayes and McKee 2009), and also certain redistricting principles are correlated to
less competitive districts (Forgette, Garner and Winkle 2009). Researchers have thus examined
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whether or not redistricting is the cause of polarization. There are studies that say redistricting is
not a cause (Abramowitz, Alexander and Gunning 2006) (McCarty, Poole and Rosenthal 2009),
and studies who use different methods to say that redistricting is a cause of polarization (Carson,
et al. 2007) (Masket, Winburn and Wright 2012). Different methods yield different results,
however it is incredibly important to distinguish between states various redistricting principles as
some may have a greater effect on the polarization of legislators.
Literature Review
Polarization
Polarization in the US Congress is the presence of more ideologically extreme members
in both parties. This has been measured by roll call voting, and has remained the standard for
measuring the level of ideological extremism of legislators. However, one study by Sulkin and
Schmitt (2014); which does not deny the existence of polarization, finds very different results
when studying legislators’ agendas. While they do find differences in the agendas of Democrats
and Republicans, those differences have remained constant. In other words, while it is consensus
that polarization has been on the rise, the agendas of individual legislators may not have become
as polarized. This comes with a few caveats however. “Given the limitations of the data utilized
here, it is not possible to ascertain whether this is because the specific policy proposals made in
legislation have become more extreme, or because committee and party agenda-setters are
pushing forward measures dealing with issues where there is more disagreement.” (Sulkin and
Schmitt 2014, 446-447) This is important because it implies that perhaps the agenda setters of
Congress are the ones who are the most extreme.
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Legislative gridlock is seen as one of the effects of the polarization of members of the US
Congress. Gridlock in this case meaning the inability to pass major legislation that may lead to
government shutdowns. Most can agree that gridlock is not good for democracy, and polarization
in the biggest factor when the parties are relatively divided. “Therefore, unified government is
just as prone to gridlock as divided government when parties are highly polarized and neither
party has a large majority. On the other hand, divided government is just as productive as unified
government when party polarization is low or when one party has a veto-proof, filibuster-proof
majority (Jones 2001, 136-137).”
One theory of causes of polarization is member adaptation and member replacement.
Member adaptation is when a member of Congress slowly becomes more polarized ideologically
over time. Member replacement is when a member of congress dies or retires and is replaced by
a more ideological member (Theriault 2006, 484). Findings show that member replacement is
responsible for two thirds of the polarization in Congress and that member adaptation is
responsible for one third of the polarization in congress. While there was a rapid increase in
polarization from the 93rd to 108th congress, it is likely that the trend will slow down due to many
ideologues having already captured their seats. (Theriault 2006, 498-499) Of course this study
only raised more questions. If 100% of the cause of polarization is member adaptation and
member replacement, what is causing both of these?
There is strong evidence that the cause of polarization is party elites and political
activists. These political activists have become more divided on many policies. This implies that
candidates become more ideologically extreme. This is particularly the case in primaries because
the voters in primaries are the political activists. “This has probably increased the incentives for
party candidates and elected officials to take ideologically extreme positions on multiple policy
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agendas, which in turn has pushed the parties’ coalitions toward more polarized positions on
various issues (Layman, Carsey and Horowitz 2006, 104).” Yet again, this raises more questions
about polarization. What has caused these political activists to become more divided on policies?
Are activists the only cause of polarization or just a part of the cause?
Research about polarization of the mass public has yielded plenty of different results
based on what was studied and their methods. If polarization of the masses could be a cause of
the polarization of the members of congress, first it must be proved that the mass public is in fact
polarized. “The literature indicates that the American public as a whole is no more polarized
today than it was a generation ago, whether we focus on general ideological orientations or
positions on specific issues (Fiorina and Abrams 2008, 584).” Party sorting has been a mixed bag
when studied. Basically, when a parties main issues become more and more correlated to each
other it becomes easier for a citizen to group themselves into that party. “For example, if half the
Democrats are northern, urban, and Catholic, and the other half southern, rural, and Evangelical,
increases in attitudinal constraint might well create larger intraparty differences rather than
interparty differences. But if subgroups become more homogeneous, cross-pressures diminish
(Fiorina and Abrams 2008, 577-582).” However, party sorting seems to imply that Congress
becomes polarized and then the citizens react by realigning, not the other way around. A third
theory of public polarization is geographic polarization- the public as a whole has not become
more polarized, but regions have become more homogenous. Many scholars discredit this saying
the United States has always had cultural differences regionally, however people with similar
incomes are grouping together, and areas are becoming less racially segregated. The problem
with these surveys is that they can only measure vote choice and not citizen preferences. (Fiorina
and Abrams 2008, 576-577)
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This short survey of literature on party polarization has revealed some of the effects of
party polarization, and some of the possible causes. With much of the research each specializing
on one theorized cause of polarization (member replacement/adaptation, political activists, public
polarization) it becomes clear that there may be many causes of polarization and not just one.
What follows next is a section of a short survey of redistricting literature. Redistricting is great to
study as a cause because it does not lead to a question of what causes it. The next section will
briefly discuss the effects of redistricting.
Redistricting
A study of redistricting and incumbent familiarity has found one of the effects of
reapportionment. When a citizen is redrawn into a new district it raises the citizens’ information
costs of voting because they now must learn about their new district and incumbent. A redrawn
citizen has about an 8% of not voting in their new district during the next midterm election. This
has implications in terms of competitiveness of elections. If states are redrawing their district
lines to make districts more competitive they must consider the trade-off being that 8% of
redrawn voters will not vote in the next election due to not knowing the incumbent (Hayes and
McKee 2009, 1019-1020). This leaves a slightly more politically active group of voters in the
district, and one of the causes of polarization could be the polarization of political activists.
Could redrawing district lines make less competitive districts?
One study on state legislatures attempts to answer this question. The study separated
states various redistricting laws apart from the main federal requirements. Identified were five
major requirements that states may or may not have when it comes to redrawing their districts:
compactness, cores/prior districts, communities of interest, political subdivisions, and
incumbency protection. These 5 different types of requirements can be summed up in 3 different
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types of laws: Form-base, population-based, and politically based. Compactness is form-based,
and has to do with how tightly-defined the district is. Political subdivisions is population based
and usually means states have to follow preexisting political boundaries. Communities of interest
(population-based), are sometimes geographic or racial but require the community to meet and
decide if the interest exists. A district core principle is population-based and requires a state to
maintain the population center of an existing district. And incumbency protection is politicallybased and it either allows or forbids consideration of incumbency status. (Forgette, Garner and
Winkle 2009, 153-155) The study found two major correlations with their principles: populationbased principles were related to margins of victory and the amount of uncontested seats, and the
states with most principles adopted have more competitive races than states who have less
redistricting principles (Forgette, Garner and Winkle 2009, 166). It is important to note that the
results show a correlation with competition and not causation, but there is still importance in the
method of studying redistricting. The acknowledgement of different redistricting principles in
each state is largely unconsidered in the study of polarization and its relation to redistricting.
Polarization & Redistricting
Another study looked at causes of falling competition in the US House races. The study
looked at three different hypothesis: redistricting, polarization, and incumbency. The author’s
results concluded that polarization and incumbency were related to competitiveness and not
redistricting. Redistricting was ruled out because of the small amount of change in competitive
districts after the redistricting cycle; all of the change happened in between cycles. This assumes
two things: the effects of redistricting on election competitiveness are immediate, and that states
with different redistricting principles are not significant. The author defends polarization with the
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fact that incumbents’ districts have included more and more partisans and also that Republican
and Democrat incumbents are less likely to represent competitive districts (Abramowitz,
Alexander and Gunning 2006).
Directly addressing polarization in Congress in terms of redistricting found that
redistricting can account for between 10-15% of polarization since the 1970s. (McCarty, Poole
and Rosenthal 2009, 667) The South is the most polarized region in the US and the study found
“gerrymandering within states has sharply increased the number of Republican congressional
districts over what it would be if districts were randomly formed from county blocks (McCarty,
Poole and Rosenthal 2009, 678).” The authors however concluded that redistricting is not the
cause of polarization. The first obvious problem is that 10-15% effect redistricting had. A 1015% effect on polarization is not huge, but it seems that redistricting is at least one of the minor
causes. Secondly, each state is treated as if it has all of the same redistricting principles, or that
none of the special redistricting principles have any effect on polarization. Finally, why not focus
on just one region of the US with high polarization? Perhaps, specific redistricting laws in The
South have had an effect on polarization.
When research was focused on a specific principle of redistricting, the results yielded a
correlation between redistricting and polarization. An article focused specifically on states with
neutral elections commissions found that the states with the commissions had more polarized
state legislatures than states without neutral elections commissions. Overall, they did find that
redistricting had a very modest effect on the level of polarization in state legislatures (Masket,
Winburn and Wright 2012). This is a great addition to the literature because it focuses on
differences between state redistricting laws, instead of treating them all the same. Specifically
focusing on who gets to draw the lines yielded different results in terms of polarization.
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A study found using a new data set that compares the amount of redistricting a state has
experienced over time that the more redistricting a state had experienced, the more extreme
partisans it had elected. “More specifically, we find that members representing new districts are
more extreme in their voting behavior compared to continuous districts. So although other
factors may be driving polarization in the aggregate, it would be premature to rule out
redistricting as playing any role in the increased polarization we see in Congress today.” (Carson,
et al. 2007, 900)
Theory
Observing aggregate changes in polarization can lead one to believe that redistricting is
not a source of polarization in Congress. Trying to prove that redistricting is the only source of
polarization will fail. However, when studies looked at states individually; whether in their
practices, principles, or changes over time, redistricting was found to have a marginal effect on
the polarization of legislatures. The literature on redistricting and polarization is limited because
it studies redistricting as a practice that has universal laws across the state. While there are
federally mandated redistricting laws that all states must follow, each states laws differ in formbased, population-based, and politically-based guidelines. When redistricting is studied in terms
of its variation across states, polarization will be related to either the number of these types of
guidelines, or certain guidelines these states have.
Hypothesis, Measurement, Data
H1: States that require form-based principles in redistricting will have congressman and state
legislators that are at average levels of polarization.
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Using Forgette, Garner, and Winkles’ data set of states redistricting principles along with DWNominate scores and a data set that measures the polarization of state legislatures.
H2: States that require population-based principles (cores/prior districts, communities of
interest, political subdivisions) will have slightly higher levels of polarization.
This is because many of the states that require population-based principles in redistricting are
states from the South. These numbers should be tested for correlation.
H3: States that require political-based principles (incumbency protection, neutral redistricting
committee) will have the highest levels of polarized congressmen and state legislators.
If political-based polarization principles are correlated to high levels of polarization among its
legislators, then this may mean that redistricting as a whole does not contribute to polarization,
but the protection of incumbents correlates to the most polarization.
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From Forgette, Garner, and Winkle (2009), pp. 154
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Conclusion
The most important thing to remember about the polarization of Congress and state
legislatures is that there are many possible causes, there is not just one overarching cause to this
problem. When studying polarization and redistricting, there are plenty of different measures and
methods that one could use and focus on. What is lacking in most literature that is focused on
redistricting is the acknowledgement of the 3 types of redistricting principles that are used in this
paper and were originally gathered by Forgette, Garner, and Winkle (2009). Redistricting is
difficult to measure as a whole because states can adopt or not require any of these 3 principles
and have a large impact on their state. Forgette, Garner, and Winkle found differences in
competition based on these principles, as well as Carson et al. (2007) finding that states with
neutral redistricting commissions had higher levels of polarization than states without them. This
paper adds to the literature in that it brings all principles of redistricting into discussion with
polarization, and that certain principles have a greater effect on polarization than others. If these
principles can be identified and fixed for a desirable outcome, then it should be done to lesson
polarization and its dire effects.
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